Buggy code:
public class CompletionScanner extends Scanner { public char [ ] completionIdentifier ; public int cursorLocation ; public int completedIdentifierStart = 0 ; public int completedIdentifierEnd = - 1 ; public static final char [ ] EmptyCompletionIdentifier = new char [ ] { } ; public CompletionScanner ( boolean assertMode ) { } public char [ ] getCurrentIdentifierSource ( ) { } public boolean getNextCharAsJavaIdentifierPart ( ) { } public int getNextToken ( ) throws InvalidInputException { this . wasAcr = false ; if ( diet ) { jumpOverMethodBody ( ) ; diet = false ; return ( currentPosition ) > ( source . length ) ? TerminalTokens . TokenNameEOF : TerminalTokens . TokenNameRBRACE ; } try { while ( true ) { withoutUnicodePtr = 0 ; int whiteStart = currentPosition ; boolean isWhiteSpace ; do { startPosition = currentPosition ; if ( ( ( currentCharacter = source [ ( ( currentPosition ) ++ ) ] ) == '\\' ) && ( ( source [ currentPosition ] ) == 'u' ) ) { isWhiteSpace = jumpOverUnicodeWhiteSpace ( ) ; } else { if ( ( recordLineSeparator ) && ( ( ( currentCharacter ) == '\r' ) || ( ( currentCharacter ) == '\n' ) ) ) pushLineSeparator ( ) ; <START_BUG> isWhiteSpace = ( ( currentCharacter ) == '<seq2seq4repair_space>' ) || ( Character . isWhitespace ( currentCharacter ) ) ; <END_BUG> } if ( ( ( ( ( whiteStart != ( currentPosition ) ) && ( ( completionIdentifier ) == null ) ) && ( whiteStart <= ( ( cursorLocation ) + 1 ) ) ) && ( ( cursorLocation ) < ( startPosition ) ) ) && ( ! ( Character . isJavaIdentifierStart ( currentCharacter ) ) ) ) { currentPosition = startPosition ; return TerminalTokens . TokenNameIdentifier ; } } while ( isWhiteSpace ) ; if ( ( tokenizeWhiteSpace ) && ( whiteStart != ( ( currentPosition ) - 1 ) ) ) { ( currentPosition ) -- ; startPosition = whiteStart ; return TerminalTokens . TokenNameWHITESPACE ; } if ( ( currentPosition ) > ( eofPosition ) ) { if ( ( ( completionIdentifier ) == null ) && ( ( startPosition ) == ( ( cursorLocation ) + 1 ) ) ) { currentPosition = startPosition ; return TerminalTokens . TokenNameIdentifier ; } return TerminalTokens . TokenNameEOF ; } switch ( currentCharacter ) { case '(' : return TerminalTokens . TokenNameLPAREN ; case ')' : return TerminalTokens . TokenNameRPAREN ; case '{' : return TerminalTokens . TokenNameLBRACE ; case '}' : return TerminalTokens . TokenNameRBRACE ; case '[' : return TerminalTokens . TokenNameLBRACKET ; case ']' : return TerminalTokens . TokenNameRBRACKET ; case ';' : return TerminalTokens . TokenNameSEMICOLON ; case ',' : return TerminalTokens . TokenNameCOMMA ; case '.' : if ( ( ( startPosition ) <= ( cursorLocation ) ) && ( ( cursorLocation ) < ( currentPosition ) ) ) { return TerminalTokens . TokenNameDOT ; } if ( getNextCharAsDigit ( ) ) return scanNumber ( true ) ; return TerminalTokens . TokenNameDOT ; case '+' : { int test ; if ( ( test = getNextChar ( '+' , '=' ) ) == 0 ) return TerminalTokens . TokenNamePLUS_PLUS ; if ( test > 0 ) return TerminalTokens . TokenNamePLUS_EQUAL ; return TerminalTokens . TokenNamePLUS ; } case '-' : { int test ; if ( ( test = getNextChar ( '-' , '=' ) ) == 0 ) return TerminalTokens . TokenNameMINUS_MINUS ; if ( test > 0 ) return TerminalTokens . TokenNameMINUS_EQUAL ; return TerminalTokens . TokenNameMINUS ; } case '~' : return TerminalTokens . TokenNameTWIDDLE ; case '!' : if ( getNextChar ( '=' ) ) return TerminalTokens . TokenNameNOT_EQUAL ; return TerminalTokens . TokenNameNOT ; case '*' : if ( getNextChar ( '=' ) ) return TerminalTokens . TokenNameMULTIPLY_EQUAL ; return TerminalTokens . TokenNameMULTIPLY ; case '%' : if ( getNextChar ( '=' ) ) return TerminalTokens . TokenNameREMAINDER_EQUAL ; return TerminalTokens . TokenNameREMAINDER ; case '<' : { int test ; if ( ( test = getNextChar ( '=' , '<' ) ) == 0 ) return TerminalTokens . TokenNameLESS_EQUAL ; if ( test > 0 ) { if ( getNextChar ( '=' ) ) return TerminalTokens . TokenNameLEFT_SHIFT_EQUAL ; return TerminalTokens . TokenNameLEFT_SHIFT ; } return TerminalTokens . TokenNameLESS ; } case '>' : { int test ; if ( ( test = getNextChar ( '=' , '>' ) ) == 0 ) return TerminalTokens . TokenNameGREATER_EQUAL ; if ( test > 0 ) { if ( ( test = getNextChar ( '=' , '>' ) ) == 0 ) return TerminalTokens . TokenNameRIGHT_SHIFT_EQUAL ; if ( test > 0 ) { if ( getNextChar ( '=' ) ) return TerminalTokens . TokenNameUNSIGNED_RIGHT_SHIFT_EQUAL ; return TerminalTokens . TokenNameUNSIGNED_RIGHT_SHIFT ; } return TerminalTokens . TokenNameRIGHT_SHIFT ; } return TerminalTokens . TokenNameGREATER ; } case '=' : if ( getNextChar ( '=' ) ) return TerminalTokens . TokenNameEQUAL_EQUAL ; return TerminalTokens . TokenNameEQUAL ; case '&' : { int test ; if ( ( test = getNextChar ( '&' , '=' ) ) == 0 ) return TerminalTokens . TokenNameAND_AND ; if ( test > 0 ) return TerminalTokens . TokenNameAND_EQUAL ; return TerminalTokens . TokenNameAND ; } case '|' : { int test ; if ( ( test = getNextChar ( '|' , '=' ) ) == 0 ) return TerminalTokens . TokenNameOR_OR ; if ( test > 0 ) return TerminalTokens . TokenNameOR_EQUAL ; return TerminalTokens . TokenNameOR ; } case '^' : if ( getNextChar ( '=' ) ) return TerminalTokens . TokenNameXOR_EQUAL ; return TerminalTokens . TokenNameXOR ; case '?' : return TerminalTokens . TokenNameQUESTION ; case ':' : return TerminalTokens . TokenNameCOLON ; case '\'' : { int test ; if ( ( test = getNextChar ( '\n' , '\r' ) ) == 0 ) { throw new InvalidInputException ( Scanner . INVALID_CHARACTER_CONSTANT ) ; }

Fix:
isWhiteSpace = ( ( currentCharacter ) == '<seq2seq4repair_space>' ) || ( isWhitespace ( currentCharacter ) ) ;